Hey all
I have a 1980 Z28 and I've been trying to get my brakes fixed for a long time now and I seem to keep getting stuck at the same problem. I'll have a firm brake pedal when the car is off, but as soon as I turn it on, the pedal goes all the way to the floor. First I thought it was air in the lines so I bled the brakes and got what little air there was out. After that didn't work I thought that maybe the master cylinder was bad or going bad so I swapped that out, twice. First one I got was faulty so I just put the new one in today and bled the brakes hoping that would solve the problem. Still same thing. What else could be wrong? Any answers would be greatly appreciated because this is driving me crazy!

 

Bench bleed the master cylinder before install?
If master cylinder is tilted upward, aka, front of cylinder points up and not bench bled, you might unbolt cylinder and with lines connected, level cylinder exercise the piston.
Unless cylinder has a bleed screw at the end, then naturally, open screw and bleed as normal.


Couple options would be to raise rear of Camaro so all air goes to the rear as you bleed, or, cover the reservoir with plate and rubber gasket and use a hand vacuum pump in sucking out air from the whole system.

 

What did you do before this problem started? Or did it just drop to the floor one day? I've seen the issue with a new master if someone got the wrong part and the operating rod between power booster and master was too long. It happens if the wrong master or master/power booster combo is put together.

 

A while back I replaced the wheel cylinders in the drums and then the car sat for a while before I got a chance to bleed the brakes. Could that have something to do with it? Air sitting in the brake lines could rust the lines or something? The master/booster combo worked fine when I first installed it. Now that I think of it, I wasn't having any problems until after I replaced the wheel cylinders. Might have to take a look at them